Answer:
The answer is A.
Explanation:
The example experiment given in the question would be a valid experiment because there is more than one variable.
For an experiment to be valid, there have to be a dependent variable, an independent variable, a constant and a control aspect.
In the example, we can say that the independent variable which has the direct effect on the aspect that we are looking for, the freezing point, is the amount of salt in the water. Therefore the dependent variable is the freezing point which is the part being observed for any change. The constant can be the amount of water used because it is static and the control can be the temperature the mixtures are exposed to which does not change throughout the experiment.
Therefore the answer is option A.
I hope this anwer helps.
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